1. Field of Invention
The present invention belongs to the technical field of electronic devices, and relates to a Micro Electromechanical System (MEMS) microphone, and specifically to a single wire programmable MEMS microphone and a programming method and system thereof.
2. Description of Related Arts
A Micro Electromechanical System (MEMS) microphone is generally formed by an MEMS sensor and a signal amplification Application Specific Integrated Circuit (ASIC). The sensitivity of the MEMS microphone refers to a voltage signal obtained at an output end of the ASIC at a sound pressure of 1 Pa. The sensitivity of the MEMS microphone depends on both the sensitivity of the MEMS sensor and the gain of the ASIC. Due to the deviation in the manufacturing process, a deviation also exists for the sensitivity of the MEMS sensor. For example, for a sensor with a sensitivity of −42 dB, a deviation of ±4 dB may exist. In some application scenario, a certain requirement is put on the deviation of the sensitivity, for example, ±1 dB.
If the MEMS microphone is required to satisfy the deviation of the sensitivity of ±1 dB, a preferred implementation solution is adjusting a gain of a circuit in the ASIC. For example, a one time programmable (OTP) memory (formed by a fuse) may be integrated in the ASIC, and the gain of the circuit is changed by changing the setting of corresponding bits in the memory. Since the packaged MEMS microphone product only has AVDD, AGND, and OUT pins, no spare pins can be used for implementing the foregoing solution. Moreover, another feasible solution may be adding a dedicated programmable PAD on an ASIC chip, but in the solution, the memory is required to be configured in a wafer-level test. Although the problem of deviation of the sensitivity is solved, the limitation on application is also increased.